net: sk_{detach|attach}_filter() rcu fixes

sk_attach_filter() and sk_detach_filter() are run with socket locked.

Use the appropriate rcu_dereference_protected() instead of blocking BH,
and rcu_dereference_bh().
There is no point adding BH prevention and memory barrier.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 6 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index 52b051f82a01..7adf50352918 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -638,10 +638,9 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
                 return err;
         }
 
-        rcu_read_lock_bh();
-        old_fp = rcu_dereference_bh(sk->sk_filter);
+        old_fp = rcu_dereference_protected(sk->sk_filter,
+                                           sock_owned_by_user(sk));
         rcu_assign_pointer(sk->sk_filter, fp);
-        rcu_read_unlock_bh();
 
         if (old_fp)
                 sk_filter_delayed_uncharge(sk, old_fp);
@@ -654,14 +653,13 @@ int sk_detach_filter(struct sock *sk)
         int ret = -ENOENT;
         struct sk_filter *filter;
 
-        rcu_read_lock_bh();
-        filter = rcu_dereference_bh(sk->sk_filter);
+        filter = rcu_dereference_protected(sk->sk_filter,
+                                           sock_owned_by_user(sk));
         if (filter) {
                 rcu_assign_pointer(sk->sk_filter, NULL);
                 sk_filter_delayed_uncharge(sk, filter);
                 ret = 0;
         }
-        rcu_read_unlock_bh();
         return ret;
 }
 EXPORT_SYMBOL_GPL(sk_detach_filter);